﻿<p>The <em>IfcRelProjectsElement</em> is an objectified relationship
between an element and one projection element that creates a
modifier to the shape of the element. The relationship is defined
to be a 1:1 relationship, if an element has more than one
projection, several relationship objects have to be used, each
pointing to a different projection element. The
<em>IfcRelProjectsElement</em> establishes an aggregation
relationship between the main element and a sub ordinary addition
feature.</p>
<blockquote class="note">
NOTE&nbsp; In contrary the
<em>IfcRelAggregates</em> relationship established an aggregation
of equal parts to a whole.
</blockquote>
<p>The <em>IfcRelProjectsElement</em> implies a Boolean operation of
addition for the geometric bodies of the element and the feature
element. As with all decomposition relationships it determines:</p>
<ul>
<li>existence dependency - the <em>RelatedFeatureElement</em>
cannot exist without the <em>RelatingElement</em></li>
<li>hierarchical and non-cyclical relationship - the
<em>IfcRelProjectsElement</em> can only alter a single
<em>IfcElement</em></li>
<li>no spatial containment - the <em>IfcFeatureElementAddition</em>
as related element never participates in the hiearchical spatial
containment relationship
<em>IfcRelContainedInSpatialStructure</em></li>
</ul>
<blockquote class="history">
HISTORY&nbsp; New entity in IFC2x2.
</blockquote>
<blockquote class="change-ifc2x4">
IFC4 CHANGE&nbsp; Supertype changed to IfcRelDecomposes.
</blockquote>